[gst-devel] gst-bad equalizer element

Christophe Dehais christophe.dehais at gmail.com
Mon Feb 12 11:10:35 CET 2007

The target application here (equalizer plugin for rhythmbox) is made
to handle the 3 elements that I know offer the 'equalizer'
functionnality: equalizer, ladsp-Eq, and ladspa-tap-equalizer. For the
last two, the gain values, advertised to be in dB are in [-48;+30] and
[-50;+20] respectively, iirc.
That's why, I'd like a dB mapping for the 'equalizer' element too, in
order to be consistent in the UI.
However I agree that for most users a value in dB doesn't mean much,
especially when going from +1dB to +2dB is not the same as going from
+11 to +12. The UI could do the mapping between dB and factor, and
lower-level gstreamer elements keep the units signal processing is
used to speak about.


On 2/12/07, James Doc Livingston <doclivingston at gmail.com> wrote:
> On Mon, 2007-02-12 at 09:39 +0100, Stefan Kost wrote:
> > This does not look like its doing a db
> > (http://en.wikipedia.org/wiki/Decibel) mapping. If '0' is no action
> > (factor 1.0) is a:
> > * value of 1 then meaning factor+1=2 aka double volume (+3db) and
> > * value of -1 then meaning a fifth of the volume (somewhere around -7db)
> > Thats what I assume, but maybe company can clarify. If its like this
> > it should be changed. The range is a bit too small imho. E.g. the EQ
> > in winamp it goes from -12db to 12 db (in media player it goes from
> > -14 to +14 whatever). I'd say -12 to +6 sounds good.
> One important questions, is whether the values should be in dB or a
> simple factor. Most applications would display a logarithmic scale, but
> the 'volume' element uses a factor, and it might be good to be
> consistent.
> Cheers,
> James "Doc" Livingston
> --
> I have hardly ever known a mathematician who was capable of reasoning.
>     -- Plato
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